[en] Observations of SMC X-1 from an Aerobee rocket and an Apollo spacecraft have detected X-ray pulsations with a period of 0.716 s. The pulsed fraction in the 1.6--10 keV energy range is 25--35 percent. Evidence for significant pulse shape and pulsed fraction changes in the 0.6--1.6 keV range is also presented. The spectrum during both observations is fitted by a photon power law, 0.040 E-0.8